Process for preparing a lignocellulose-based product, and product obtainable by the process

ABSTRACT

A process for the manufacture of a lignocellulose-based product from a lignocellulosic material comprises treating the lignocellulosic material and a phenolic polysaccharide having substituents containing a phenolic hydroxy group with an enzyme capable of catalyzing the oxidation of phenolic groups in the presence of an oxidizing agent.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 35 U.S.C. 371 national application ofPCT/DK95/00318 filed 26 Jul. 1995, which is incorporated herein byreference.

FIELD OF THE INVENTION

The present invention provides a process for producing alignocellulose-based product, e.g. fibre board such as hardboard ormedium-density fibre board ("MDF")!, particle board, plywood, paper orpaperboard (such as cardboard and linerboard), from an appropriatelignocellulosic starting material, such as vegetable fibre, wood chips,wood flakes, etc. The use of the process of the invention confersexcellent tensile, tear and compression strength on lignocellulose-basedproducts prepared thereby, especially paper products such as linerboard, cardboard and corrugated board.

BACKGROUND AND BRIEF DESCRIPTION OF THE INVENTION

Lignocellulose-based products prepared from lignocellulosic startingmaterials, notably products manufactured starting from vegetable fibre(e.g. wood fibre) prepared by mechanical or mechanical/chemicalprocedures (the latter often being denoted "semi-chemical" procedures),or by a chemical procedure without bleaching, or from wood particles(wood "chips", flakes and the like), are indispensable everydaymaterials. Some of the most familiar types of such products includepaper for writing or printing, cardboard, corrugated cardboard, fibreboard (e.g. "hardboard"), and particle board.

Virtually all grades of paper, cardboard and the like are produced fromaqueous pulp slurry. Typically, the pulp is suspended in water, mixedwith various additives and then passed to equipment in which the paper,cardboard etc. is formed, pressed and dried. Irrespective of whethermechanically produced pulp (hereafter denoted "mechanical pulp"),semi-chemically produced pulp (hereafter denoted "semi-chemical pulp"),unbleached chemical pulp or pulp made from recycled fibres (i.e. pulpprepared from recycled paper, rags and the like) is employed, it isoften necessary to add various strengthening agents to the pulp in orderto obtain an end product having adequate strength properties. In thecase of paper and board for use in packaging and the like, the tensilestrength and tear strength under dry and wet conditions are of primaryimportance; moreover, notably in the case of certain grades of cardboard(e.g. so-called unbleached board for the manufacture of corrugatedcardboard boxes for packaging, transport and the like), the compressionstrength of the material is often also an important factor. Among thestrengthening agents used today there are a number of environmentallyundesirable substances which it would be desirable to replace by moreenvironmentally acceptable materials. As examples hereof may bementioned epichlorohydrin, urea-formaldehyde and melamine-formaldehyde.

In the case of "traditional" lignocellulose-based composites for use inbuilding construction, flooring, cladding, furniture, packaging and thelike, such as hardboard (which is normally made from wood fibresproduced by mechanical or semi-chemical means or by so-called "steamexplosion") and particle board (which is made from relatively coarsewood particles, fragments or "chips"), binding of the wood fibres orparticles to give a coherent mass exhibiting satisfactory strengthproperties can be achieved using a process in which the fibres/particlesare treated--optionally in a mixture with one or more "extenders", suchas lignosulfonates and/or kraft lignin--with synthetic adhesives(typically adhesives of the urea-formaldehyde, phenol-formaldehyde orisocyanate type) and then pressed into the desired form (boards, sheets,panels etc.) with the application of heat.

The use of synthetic adhesives of the above-mentioned types in theproduction of wood products is, however, generally undesirable from anenvironmental and/or safety point of view, since many such adhesives aredirectly toxic--and therefore require special handlingprecautions--and/or can at a later stage give rise to release of toxicand/or environmentally harmful substances; thus, for example, therelease of formaldehyde from certain cured formaldehyde-based adhesives(used as binders in, e.g., particle board and the like) has beendemonstrated.

In the light of the drawbacks associated with the use of syntheticadhesives as binders in the manufacture of lignocellulose-basedproducts, considerable effort has been devoted in recent years to thedevelopment of binder systems and binding processes which are moreacceptable from an environmental and toxicity point of view, andrelevant patent literature in this respect includes the following:

EP 0 433 258 A1 discloses a procedure for the production of mechanicalpulp from a fibrous product using a chemical and/or enzymatic treatmentin which a "binding agent" is linked with the lignin in the fibrousproduct via the formation of radicals on the lignin part of the fibrousproduct. This document mentions "hydrocarbonates", such as cationicstarch, and/or proteins as examples of suitable binding agents. Asexamples of suitable enzymes are mentioned laccase, lignin peroxidaseand manganese peroxidase, and as examples of suitable chemical agentsare mentioned hydrogen peroxide with ferro ions, chlorine dioxide,ozone, and mixtures thereof.

EP 0 565 109 A1 discloses a method for achieving binding of mechanicallyproduced wood fragments via activation of the lignin in the middlelamella of the wood cells by incubation with phenol-oxidizing enzymes.The use of a separate binder is thus avoided by this method.

U.S. Pat. No. 4,432,921 describes a process for producing a binder forwood products from a phenolic compound having phenolic groups, and theprocess in question involves treating the phenolic compound with enzymesto activate and oxidatively polymerize the phenolic compound, therebyconverting it into the binder. The only phenolic compounds which arespecifically mentioned in this document, or employed in the workingexamples given therein, are lignin sulfonates, and a main purpose of theinvention described in U.S. Pat. No. 4,432,921 is the economicexploitation of so-called "sulfite spent liquor", which is a liquidwaste product produced in large quantities through the operation of thewidely-used sulfite process for the production of chemical pulp, andwhich contains lignin sulfonates.

With respect to the use of lignin sulfonates--in particular in the formof sulfite spent liquor--as phenolic polymers in systems/processes forbinding wood products (as described in U.S. Pat. No. 4,432,921), thefollowing comments are appropriate:

(i) subsequent work (see H. H. Nimz in Wood Adhesives, Chemistry andTechnology, Marcel Dekker, New York and Basel 1983, pp. 247-288), and AHaars et al. in Adhesives from Renewable Resources, ACS Symposium Series385, American Chemical Society 1989, pp. 126-134) has demonstrated thatby comparison with the amounts of "traditional" synthetic adhesiveswhich are required in the manufacture of wood-based boards, very largeamounts of lignin sulfonates are required in order to achieve comparablestrength properties;

(ii) the pressing time required when pressing wood-based board productsprepared using lignin sulfonate binders has been found to be very longsee E. Roffael and B. Dix, Holz als Roh- und Werkstoff 49 (1991)199-205!;

(iii) lignin sulfonates available on a commercial scale are generallyvery impure and of very variable quality see J. L. Philippou, Journal ofWood Chemistry and Technology 1(2) (1981) 199-227!;

(iv) the very dark colour of spent sulfite liquor renders it unsuited asa source of lignin sulfonates for the production of, e.g., paperproducts (such as packaging paper, linerboard or unbleached board forcardboard boxes and the like) having acceptable colour properties.

The present inventors have surprisingly found that binding oflignocellulosic materials (vegetable fibres, wood chips, etc.) using acombination of a polysaccharide having at least substituents containinga phenolic hydroxy group (in the following often simply denoted a"phenolic polysaccharide"), an oxidizing agent and an enzyme capable ofcatalyzing the oxidation of phenolic groups by the oxidizing agent canbe employed in the manufacture of lignocellulose-based productsexhibiting strength properties at least comparable to, and oftensignificantly better than, those achievable using previously knownprocesses which have attempted to reduce or avoid the use of toxicand/or otherwise harmful substances such as the processes described inEP 0 433 258 A1, EP 0 565 109 A1 and U.S. Pat. No. 4,432,921 (videsupra)!.

Thus, for example, the amount of binder required to preparelignocellulose-based products of very satisfactory strength by theprocess of the present invention is generally much lower typically by afactor of about three or more--than the level of binder (based on ligninsulfonate) required to obtain comparable strength properties using theprocess according to U.S. Pat. No. 4,432,921. The process according tothe present invention can thus not only provide an environmentallyattractive alternative to more traditional binding processes employingsynthetic adhesives, but it can probably also compete economically withsuch processes.

DETAILED DESCRIPTION OF THE INVENTION

The present invention thus provides a process for the manufacture of alignocellulose-based product from a lignocellulosic material, theprocess comprising treating said lignocellulosic material and a phenolicpolysaccharide (i.e. a polysaccharide which is substituted with at leastsubstituents containing a phenolic hydroxy group) with an enzyme capableof catalyzing the oxidation of phenolic groups in the presence of anoxidizing agent.

The order of mixing/contacting the four components, i.e. thelignocellulosic material, the phenolic polysaccharide, the enzyme andthe oxidizing agent, is unimportant as long as the process set-upensures that the activated lignocellulosic material and the activatedphenolic polysaccharide are brought together in a way that enables themto react in the desired manner. Thus, for example, the enzyme and theoxidizing agent may be mixed with the lignocellulosic material before orafter being mixed with the phenolic polysaccharide.

It will generally be appropriate to incubate the reaction medium(containing the lignocellulosic material, phenolic polysaccharide andenzyme in the presence of oxidizing agent) for a period of at least afew minutes. An incubation time of from 1 minute to 10 hours willgenerally be suitable, although a period of from 1 minute to 2 hours ispreferable.

As already indicated, the process of the invention is well suited to theproduction of all types of lignocellulose-based products, e.g. varioustypes of fibre board (such as hardboard), particle board, flakeboardsuch as oriented-strand board ("OSB")!, plywood, moulded composites(e.g. shaped articles based on wood particles, often in combination withother, non-lignocellulosic materials, e.g. certain plastics), paper andpaperboard (such as cardboard, linerboard and the like).

The lignocellulosic starting material employed in the method of theinvention can be in any appropriate form, e.g. in the form of vegetablefibre (such as wood fibre), wood chips, wood flakes or wood veneer,depending on the type of product to be manufactured. If appropriate, alignocellulosic material can be used in combination with anon-lignocellulosic material having phenolic hydroxy functionalities.Using the process of the invention, intermolecular linkages between thelignocellulosic material and the non-lignocellulosic material,respectively, may then be formed (i.e. in a manner analogous to that inwhich intermolecular linkages are formed when lignocellulosic materialsalone are employed in the process), resulting in a composite product.Besides functioning as a good adhesive/binder, the phenolicpolysaccharide also serves as a good "gap-filler", which is a bigadvantage when producing, e.g., particle boards from large woodparticles.

It will normally be appropriate to employ the lignocellulosic materialin question in an amount corresponding to a weight percentage of drylignocellulosic material dry substance (DS)! in the medium in the rangeof 0.1-90%.

The temperature of the reaction mixture in the process of the inventionmay suitably be in the range of 10°-120° C., as appropriate; however, atemperature in the range of 15°-90° C. is generally to be preferred. Asillustrated by the working examples provided herein (vide infra), thereactions involved in a process of the invention may take place verysatisfactorily at ambient temperatures around 20° C.

Phenolic Polysaccharides

The phenolic polysaccharides employed in the process of the inventionmay suitably be materials obtainable from natural sources (vide infra)or polysaccharides which have been chemically modified by theintroduction of substituents having phenolic hydroxy groups. Examples ofthe latter category are modified starches containing phenolicsubstituents, e.g. acyl-type substituents derived fromhydroxy-substituted benzoic acids (such as, e.g., 2-, 3- or4-hydroxybenzoic acid).

The phenolic substituent(s) in phenolic polysaccharides suited for usein the context of the present invention may suitably be linked to thepolysaccharide species by, e.g., ester linkages or ether linkages.

Very suitable phenolic polysaccharides are those in which the phenolicsubstituent of the phenolic polysaccharide is a substituent derived froma phenolic compound which occurs in at least one of the followingplant-biosynthetic pathways: from p-coumaric acid to p-coumaryl alcohol,from p-coumaric acid to coniferyl alcohol and from p-coumaric acid tosinapyl alcohol; p-coumaric acid itself and the three mentioned "endproducts" of the latter three biosynthetic pathways are also relevantcompounds in this respect. Examples of relevant "intermediate" compoundsformed in these biosynthetic pathways include caffeic acid, ferulic acid(i.e. 4-hydroxy-3-methoxycinnamic acid), 5-hydroxy-ferulic acid andsinapic acid.

Particularly suitable phenolic polysaccharides are those which exhibitgood solubility in water, and thereby in aqueous media in the context ofthe invention. In this and other respects, a number of types of phenolicpolysaccharides which are readily obtainable in uniform quality fromvegetable sources have been found to be particularly well-suited for usein the process of the present invention. These include, but are in noway limited to, phenolic arabino- and heteroxylans, and phenolicpectins. Very suitable examples hereof are ferulylated arabinoxylans(obtainable, e.g., from wheat bran or maize bran) and ferulylatedpectins (obtainable from, e.g., beet pulp), i.e. arabinoxylans andpectins containing ferulyl substituents attached via ester linkages tothe polysaccharide molecules.

The amount of phenolic polysaccharide employed in the process of theinvention will generally be in the range of 0.01-10 weight per cent,based on the weight of lignocellulosic material (calculated as drylignocellulosic material), and amounts in the range of about 0.02-6weight per cent (calculated in this manner) will often be very suitable.

Enzymes

In principle, any type of enzyme capable of catalyzing oxidation ofphenolic groups may be employed in the process of the invention.Preferred enzymes are, however, oxidases e.g. laccases (EC 1.10.3.2),catechol oxidases (EC 1.10.3.1) and bilirubin oxidases (EC 1.3.3.5)! andperoxidases (EC 1.11.1.7). In some cases it may be appropriate to employtwo or more different enzymes in the process of the invention.

Among types of oxidases (in combination with which oxygen--e.g.atmospheric oxygen--is an excellent oxidizing agent), laccases haveproved to be well suited for use in the method of the invention.

Laccases are obtainable from a variety of microbial sources, notablybacteria and fungi (including filamentous fungi and yeasts), andsuitable examples of laccases include those obtainable from strains ofAspergillus, Neurospora (e.g. N. crassa), Podospora, Botrytis, Collybia,Fomes, Lentinus, Pleurotus, Trametes some species/strains of which areknown by various names and/or have previously been classified withinother genera; e.g. Trametes villosa=T. pinsitus=Polyporus pinsitis (alsoknown as P. pinsitus or P. villosus)=Coriolus pinsitus!, Polyporus,Rhizoctonia (e.g. R. solani), Coprinus (e.g. C. plicatilis), Psatyrella,Myceliophthora (e.g. M. thermophila), Schytalidium, Phlebia (e.g. P.radita; see WO 92/01046), or Coriolus (e.g. C.hirsutus; see JP2-238885).

A preferred laccase in the context of the invention is that obtainablefrom Trametes villosa.

Peroxidase enzymes (EC 1.11.1) employed in the method of the inventionare preferably peroxidases obtainable from plants (e.g. horseradishperoxidase or soy bean peroxidase) or from microorganisms, such as fungior bacteria. In this respect, some preferred fungi include strainsbelonging to the sub-division Deuteromycotina, class Hyphomycetes, e.g.Fusarium, Humicola, Tricoderma, Myrothecium, Verticillum, Arthromyces,Caldariomyces, Ulocladium, Embellisia, Cladosporium or Dreschlera, inparticular Fusarium oxysporum (DSM 2672), Humicola insolens, Trichodermaresii, Myrothecium verrucana (IFO 6113), Verticillum alboatrum,Verticillum dahlie, Arthromyces ramosus (FERM P-7754), Caldariomycesfumago, Ulocladium chartarum, Embellisia alli or Dreschlera halodes.

Other preferred fungi include strains belonging to the sub-divisionBasidiomycotina, class Basidiomycetes, e.g. Coprinus, Phanerochaete,Coriolus or Trametes, in particular Coprinus cinereus f. microsporus(IFO 8371), Coprinus macrorhizus, Phanerochaete chrysosporium (e.g.NA-12) or Trametes versicolor (e.g. PR4 28-A).

Further preferred fungi include strains belonging to the sub-divisionZygomycotina, class Mycoraceae, e.g. Rhizopus or Mucor, in particularMucor hiemalis.

Some preferred bacteria include strains of the order Actinomycetales,e.g. Streptomyces spheroides (ATTC 23965), Streptomyces thermoviolaceus(IFO 12382) or Streptoverticillum verticillium ssp. verticillium.

Other preferred bacteria include Bacillus pumilus (ATCC 12905), Bacillusstearothermophilus, Rhodobacter sphaeroides, Rhodomonas palustri,Streptococcus lactis, Pseudomonas purrocinia (ATCC 15958) or Pseudomonasfluorescens (NRRL B-11).

Further preferred bacteria include strains belonging to Myxococcus, e.g.M. virescens.

Other potential sources of useful particular peroxidases are listed inB. C. Saunders et al., Peroxidase, London 1964, pp. 41-43.

When employing laccases in the process of the invention, an amount oflaccase in the range of 0.02-2000 laccase units (LACU) per gram of drylignocellulosic material will generally be suitable; when employingperoxidases, an amount thereof in the range of 0.02-2000 peroxidaseunits (PODU) per gram of dry lignocellulosic material will generally besuitable.

Determination of Oxidase and Peroxidase Activity

The determination of oxidase (e.g. laccase) activity is based on theoxidation of syringaldazin to tetramethoxy azo bis-methylene quinoneunder aerobic conditions, and 1 LACU is the amount of enzyme whichconverts 1 μM of syringaldazin per minute under the followingconditions: 19 μM syringaldazin, 23.2 mM acetate buffer, 30° C., pH 5.5,reaction time 1 minute, shaking; the reaction is monitoredspectrophotometrically at 530 nm.

With respect to peroxidase activity, 1 PODU is the amount of enzymewhich catalyses the conversion of 1 μmol of hydrogen peroxide per minuteunder the following conditions: 0.88 mM hydrogen peroxide, 1.67 mM2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate), 0.1M phosphatebuffer, pH 7.0, incubation at 30° C.; the reaction is monitoredphotometrically at 418 nm.

Oxidizing Agents

The enzyme(s) and oxidizing agent(s) used in the process of theinvention should clearly be matched to one another, and it is clearlypreferable that the oxidizing agent(s) in question participate(s) onlyin the oxidative reaction involved in the binding process, and does/donot otherwise exert any deleterious effect on the substances/materialsinvolved in the process.

Oxidases, e.g. laccases, are, among other reasons, well suited in thecontext of the invention since they catalyze oxidation by molecularoxygen. Thus, reactions taking place in vessels open to the atmosphereand involving an oxidase as enzyme will be able to utilize atmosphericoxygen as oxidant; it may, however, be desirable to forcibly aerate thereaction medium during the reaction to ensure an adequate supply ofoxygen.

In the case of peroxidases, hydrogen peroxide is a preferred peroxide inthe context of the invention and is suitably employed in a concentration(in the reaction medium) in the range of 0.01-100 mM.

pH in the Reaction Medium

Depending, inter alia, on the characteristics of the enzyme(s) employed,the pH in the aqueous medium (reaction medium) in which the process ofthe invention takes place will be in the range of 3-10, preferably inthe range 4-9.

The present invention also relates to a lignocellulose-based productobtainable by a process according to the invention as disclosed herein.

EXAMPLES

The ferulylated arabinoxylan used in the examples (often referred tobelow simply as arabinoxylan) below was obtained from G B Gels Ltd,Swansea, Wales, UK. The laccase employed was Trametes villosa laccase,produced by Novo Nordisk A/S, Bagsvaerd, Denmark.

Example 1

Hard boards (1000 kg/m²) of birch NSSC pulp were formed in a PFI sheetmould. The wet board was pressed at room temperature to a dry mattercontent of 50%.

After pressing, the boards were placed on a net and immersed indifferent solutions. In all cases, the boards were immersed for 90seconds. The temperature of the solutions was 20° C.

The different treatments were as follows:

Arabinoxylan:

immersed in a solution of ferulylated arabinoxylan (0.6% w/w).

Arabinoxylan+laccase:

immersed in a freshly made solution of ferulylated arabinoxylan (0.6%w/w) and laccase (1 LACU/ml).

After immersion, the boards were left at room temperature for 5 minutesand then pressed at room temperature to a dry matter content of around50%. The wet boards were pressed in a hot press for 5 minutes at 180° C.to form a hard board. All the boards were pressed to a thickness of 3mm.

The boards were tested for bending strength MOE (modulus of elasticity)and MOR (modulus of rupture)! according to the European Standard EN310:1993. The results are listed in the table below. The values are theaverage of results obtained for the two sides of the boards produced bythe wet fibreboard process.

    ______________________________________                                                          MOE  MOR                                                                      (GPa)                                                                              (MPa)                                                  ______________________________________                                        Arabinoxylan        3.64   42.7                                               Arabinoxylan + laccase                                                                            4.16   59.0                                               ______________________________________                                    

It is seen that the MOE and MOR values for the board produced accordingto the invention are much higher than the values obtained when addingonly ferulylated arabinoxylan to the fibres.

Example 2

Handsheets of pine TMP pulp (160 g/m²) were made in a PFI sheet mould.The sheets were then pressed in a sheet press for 5 minutes at apressure of 400 kPa. After pressing, the wet sheets were placed on a netand immersed in different solutions. In all cases the sheets wereimmersed for 90 seconds, and the temperature of the solutions was 20° C.

The different treatments were as follows:

Control:

immersed in water

Laccase:

immersed in a solution of laccase (0.1 LACU/ml).

Arabinoxylan:

immersed in a solution of ferulylated arabinoxylan (0.6% w/w).

Arabinoxylan+laccase:

immersed in a freshly made solution of ferulylated arabinoxylan (0.6%w/w) and laccase (0.1 LACU/ml).

After immersion, the sheets were left at room temperature for 5 minutesand then pressed in the sheet press for 5 minutes at a pressure of 400kPa. After pressing, the sheets were dried in a sheet dryer. The dryinglasted 5 minutes.

Thickness and tensile index were measured for the sheets according tothe SCAN standards SCAN-P7 and SCAN-P16. the results are given below. Itis clearly seen that the sheets treated according to the invention aremuch stronger than the control and the sheets treated with only one ofthe components.

The results of the thickness measurement indicate that the treatmentaccording to the invention also prevent "springback" of the sheet whenthe pressure is released after the final pressing. It is observed thatthe thickness of the sheets treated according to the invention is onlyhalf that of the control and reference sheets.

    ______________________________________                                                       Tensile index                                                                          Thickness                                                            (Nm/g)   (μm)                                               ______________________________________                                        Control          8.106      694                                               Arabinoxylan     7.309      639                                               Laccase          5.257      682                                               Arabinoxylan + Laccase                                                                         46.95      350                                               ______________________________________                                    

A qualitative test of the wet strength demonstrated that the sheetsproduced according to the invention have significantly higher tensilestrength than the controls after immersion in tap water for 3 hours.

Example 3

Two pieces of birch wood were uniformly coated with a solutioncontaining ferulylated arabinoxylan (2% w/w) and laccase (0.25 LACU/ml)on the sides to be bonded. The two pieces were pressed together at apressure of 400 KPa at room temperature for 30 minutes.

Two sets of control experiments were made: one with only laccase in thesolution and one with only the arabinoxylan in the solution. The pieceswere treated as described above.

After drying/hardening, the bonding strength was measured according tothe DIN standard.

    ______________________________________                                                       Bond strength                                                  ______________________________________                                        Only laccase added                                                                             The pieces did not adhere                                    Only arabinoxylan added                                                                        0.4 MPa                                                      Arabinoxylan + laccase added                                                                   1.6 MPa                                                      ______________________________________                                    

It is clearly seen that the process according to the invention gives amuch better adhesive effect than obtained when adding only one of thetwo active components (i.e. the laccase and the ferulylatedarabinoxylan).

We claim:
 1. A process for the manufacture of a lignocellulose product,comprising the steps of:(a) mixing in a reaction medium, a phenolicpolysaccharide with lignocellulose, wherein the polysaccharide issubstituted with a phenolic hydroxy group; and (b) adding to the mixtureof (a) an enzyme capable of catalyzing the oxidation of phenolic groupsin the presence of an oxidizing agent.
 2. The process according to claim1, wherein said lignocellulose product is selected from the groupconsisting of fibre board, particle board, flakeboard, plywood andmoulded composites.
 3. The process according to claim 1, wherein saidlignocellulose product is selected from the group consisting of paperand paperboard.
 4. The process according to claim 1, wherein saidlignocellulose is selected from the group consisting of vegetable fibre,wood fibre, wood chips, wood flakes and wood veneer.
 5. The processaccording to claim 1, wherein the phenolic substituent is selected fromthe group consisting of p-coumaric acid, p-coumaryl alcohol, coniferylalcohol, sinapyl alcohol, ferulic acid and p-hydroxybenzoic acid.
 6. Theprocess according to claim 1, wherein the polysaccharide portion of thephenolic polysaccharide is selected from the group consisting ofmodified and unmodified starches, modified and unmodified cellulose, andmodified and unmodified hemicelluloses.
 7. The process according toclaim 1, wherein said phenolic polysaccharide is selected from the groupconsisting of ferulylated arabinoxylans and ferulylated pectins.
 8. Theprocess according to claim 1, wherein a reaction medium containing saidlignocellulose, said phenolic polysaccharide and said enzyme isincubated in the presence of said oxidizing agent for a period of from 1minute to 10 hours.
 9. The process of claim 8, wherein the enzyme isincubated in the presence of said oxidizing agent for a period of from 1minute to 2 hours.
 10. The process according to claim 1, wherein saidenzyme is selected from the group consisting of oxidases andperoxidases.
 11. The process according to claim 1, wherein said enzymeis an oxidase selected from the group consisting of laccases (EC1.10.3.2), catechol oxidases (EC 1.10.3.1) and bilirubin oxidases (EC1.3.3.5), and said oxidizing agent is oxygen.
 12. The process accordingto claim 11, wherein said enzyme is a laccase and is used in an amountin the range of 0.02-2000 LACU per g of dry lignocellulose.
 13. Theprocess of claim 11, wherein the mixture of step (b) is aerated.
 14. Theprocess of claim 11, wherein said enzyme is a laccase obtained from afungus of the genus Botrytis, Myceliophthora, or Trametes.
 15. Theprocess of claim 14, wherein the fungus is Trametes versicolor orTrametes villosa.
 16. The process according to claim 1, wherein saidenzyme is a peroxidase and said oxidizing agent is hydrogen peroxide.17. The process according to claim 16, wherein said peroxidase is usedin an amount in the range of 0.02-2000 PODU per g of dry lignocellulose,and the initial concentration of hydrogen peroxide in the medium is inthe range of 0.01-100 mM.
 18. The process according to claim 1, whereinthe amount of lignocellulose employed corresponds to 0.1-90% by weightof the reaction medium, calculated as dry lignocellulose.
 19. Theprocess according to claim 1, wherein the temperature of the reactionmedium is in the range of 10°-120° C.
 20. The process of claim 19,wherein the temperature of the reaction medium is in the range of15°-90° C.
 21. The process according to claim 1, wherein an amount ofphenolic polysaccharide in the range of 0.1-10% by weight.
 22. Theprocess according to claim 1, wherein the pH in the reaction medium isin the range of 3-10.
 23. The process of claim 22 wherein the pH in thereaction medium is in the range of 4-9.
 24. A lignocellulose productobtainable by the process according to claim 1.